Can We Please Get EV Motors Out of the Actual Car?

Porsche raced hub motors 127 years ago. Now Orbis offers the torque, cost, and unsprung weight that may finally move motors back out to our wheels.

Nineteenth-century electric cars were as likely to use inboard motors as they were wheel-hub motors. OG car-guy Ferdinand Porsche raced a wheel-hub-motored EV in Vienna, Austria, in 1897, and Lohnerandothers built production versions from 1900 to 1920. Porsche employed a direct drive that eliminated the friction of a geared or chain drive, but his motors also lacked the torque multiplication such drives offer. So the copper and iron required to generate sufficient torque to accelerate his heavy batteries resulted in 320-pound motors.

That much unsprung weight seriously degrades a vehicle’s ride quality and dynamic handling while adding considerable cost, and motors at the wheels experience way more shock, vibration, and risk of contamination. As a result, few EVs have used wheel-hub motors since. (Lightyear and Lordstown Motors produced a few such vehicles before going bankrupt, each using Elaphe wheel-hub motors.) But recent developments indicate the concept is ripe for a renaissance—like the $30 million investment BMW just made in hub motor supplier DeepDrive.

Back in 2018, Orbis Wheels demonstrated a hub-mounted motor that solved Porsche’s torque-multiplication problem by driving a pinion gear that spun a ring gear on the wheel. We tested Orbis’ proof-of-concept vehicle, a Honda Civic Type R with two 50-hp/70-lb-ft e-bike motors driving the rear wheels. They shaved 1.7 seconds off the 0–60 time. By also employing a small brake caliper engaging the inside of a larger-diameter, thinner, wheel-mounted rotor, weight savings in the brake system effectively offset the motor’s unsprung weight.

That setup was hopelessly noisy and fragile, but continuous innovation and development has refined it sufficiently that it’s now attracting OEM and aftermarket production interest.

exploded view with callouts

Orbis Innovation No. 1: Modular Tunable Axial Flux Motor

“Pancake” style axial-flux motors sandwich a disclike permanent-magnet rotor between stator discs. Orbis’ version is tunable in two ways: For the strongest, skinniest setup imaginable, spec a single rotor fitted with rare-earth magnets. Applications with a bit more depth but less budget to work with can fit a second rotor and use domestic ferrite magnets. Orbis can fine-tune output by blending rare-earth and ferrite magnets on the rotors. Reducing rare-earth materials lowers cost and sourcing woes, reduces heat generated, improves efficiency, and allows motors to cope better with “field weakening” at higher speeds (stator field strength drops, lowering torque while maintaining constant power). This allows one basic design to deliver between 184 and 738 lb-ft.

Orbis Innovation No. 2: Planetary Torque Multiplication

Those figures sound impressive in our motor-shaft output frame of reference, but today’s EV motors power a reduction drive that multiplies the torque—typically by something like 8:1. Orbis achieves torque multiplication at the wheel hub using a simple planetary reduction gear that fits roughly the space otherwise consumed by a halfshaft’s constant-velocity joint and provides multiplication ranging from 2.50:1 to 5.25:1.

This is not a new idea: In 1884, Missourian Wellington Adams was awarded U.S. patent US300827A for a similar concept applied to an electric train wheel motor. Today such reduction gearing is somewhat common in e-bikes, but no other established player in the EV wheel-motor game uses it. And Orbis’ internal gearing solution already meets OEM noise targets.

Three Important Variables

OEMs looking to get an affordable PHEV to market can electrify an undriven axle with two rare-earth-free single-rotor 184-lb-ft motors capable of delivering between 922 and 1,936 lb-ft to the axle, depending on gearing. Switching to rare-earth magnets or adding a second pair of rotors doubles those numbers; doing both doubles them again. These two little wheel-hub motors therefore can simulate a single inboard motor running 8:1 gearing that makes between 115 and 968 lb-ft.

Orbis Electric Output, lb-ft
Single Rotor	Dual Rotor
Output at the motor	184	369	369	738
Axle	2.50:1 motor gear	922	1,844	1,844	3,688
Torque	5.25:1 motor gear	1,936	3,872	3,872	7,744

With 0 percent rare-earth magnets (e.g. ferrite)

With 100 percent rare-earth magnets (e.g. neodymium)

Unsprung Mass and Performance

A major global OEM held an event to evaluate hub-motor options for electrifying existing vehicles, inviting DeepDrive, Elaphe, Protean, and Orbis. Before evaluating these motors, it outfitted a combustion sports car from its range with about 50 pounds of dead weight added to each wheel at one axle. Only three participants could correctly identify which of two otherwise identical cars bore the added unsprung mass.

Still, extensive experience optimizing torque per mass gave Orbis a specific-torque advantage, delivering 49 to 117 percent better wheel-torque/weight than its direct-drive competitors. Orbis’ demo motors added about 25 pounds at each corner, but production-grade ones would only add about 5 pounds, and the car should end up at least 50 to 100 pounds lighter. These savings enable switching from NMC batteries to cheaper, bulkier, heavier iron-phosphate chemistry with little or no range, cost, weight, or packaging penalty.

The OEM demo was based on a legacy EV model with the inboard motor removed. The test car was battery-power constrained to roughly half the total rated output of Orbis’ two motors, leaving 0–60 performance unchanged, but the demo car gained torque-vectoring capability, and removing the inboard motor freed up useful passenger/cargo volume.

What About Durability?

Because the motor housing serves as the suspension upright and conducts all tire-to-suspension loads, it’s very rigid. Sealing is to IP67 standards (dust tight and water-tight for 30 minutes at 3 feet deep), and Orbis retains OEM wheel bearings. And with proper strain-relief precautions, the high-voltage wiring and glycol coolant plumbing connections aren’t problematic.

Aftermarket Opportunities

Orbis spent two years certifying a kit to electrify the non-driven axle of a delivery van that takes just three hours to install. On a Ford Transit, using a 14-kWh NMC battery in a market where fuel costs $5 per gallon should return $2,650 in annual fuel savings, easily paying back a $16,000 upfront cost. And the above global OEM’s PHEV fitment shares a platform with a North American market vehicle that’s popular with the tuner set, so there’s aftermarket interest in productionizing an Orbis AWD retrofit kit (perhaps with media drives later this year).

An Application We Didn’t See Coming

Did you know refrigerated semi-trailers use their own diesel engines? All-electric alternatives require a very large battery plus Level 2 or Level 3 charging. Using simpler air-cooled versions of Orbis wheel motors to generate power—23 kW during braking, 9 kW continuous while cruising—allows the battery size to be cut in half. This setup is already on sale, helping lower costs to electrify refrigerated trucking fleets.

I have to wonder: Where would the world be right now had Ferdinand Porsche met Wellington Adams back in the day? Might lightweight, geared electric hub motors have established a powertrain status quo?